Asia Oceania Journal of Nuclear Medicine and Biology (Oct 2013)

Is Tc99m-MIBI scintigraphy a predictor of response to pre-operative neoadjuvant chemotherapy in Osteosarcoma?

  • Mohammad Gharehdaghi,
  • Vahidreza Dabbagh Kakhki,
  • Alireza Khouei,
  • Gholamhosein Novferesti,
  • Alireza Houtkani,
  • Mahdi Farzadnia,
  • Ramin Sadeghi

Journal volume & issue
Vol. 1, no. 2
pp. 22 – 27

Abstract

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Introduction: Multidrug resistance (MDR), which may be due to the over expression of P-glycoprotein (Pgp) and/or MRP, is a major problem in neoadjuvant chemotherapy of osteosarcoma. The aim of this study was to investigate the role of Tc-99m MIBI scan for predicting the response to pre-operative chemotherapy. Materials and Methods: Twenty-five patients (12 males and 13 females, aged between 8 and 52y) with osteosarcoma were studied. Before the chemotherapy, planar 99mTc-MIBI anterior and posterior images were obtained 10-min [tumor-to-background ratio: (T1/B1)10min] and 3-hr after tracer injection. After completion of chemotherapy, again 99mTc-MIBI scan was performed at 10-min after tracer injection. In addition to calculation of decay corrected tumor to background (T/B) ratios , using the 10-min and 3-hr images of the pre-chemotherapy scintigraphy , percent wash-out rate (WR%) of 99mTc-MIBI was calculated. Using the 10-min images of the pre- and post-chemotherapy scans, the percent reduction in uptake at the tumor site after treatment (Red%) was also calculated. Then after surgical resection, tumor response was assessed by percentage of necrosis. Results: All patients showed significant 99mTc-MIBI uptake in early images. Only 9 patients showed good response to chemotherapy (necrosis≥90%) while 16 patients were considered as non-responder (necrosis<90%). There was no statistical significant difference between non-responders and responders in (T1/B1)10min.There was a significant negative correlation between WR% and percentage of necrosis (P=0.001). On the other hand, there was a significant correlation between Red% and percentage of necrosis (P<0.001).There was also statistical significant difference in WR% and Red% between non-responders and responders (both P< 0.001). Conclusion: Washout rate of 99mTc-MIBI in pre-chemotherapy scintigraphy as well as Red% using pre- and post-chemotherapy MIBI scintigraphy are useful methods for predicting response to neoadjuvant chemotherapy

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